>> Maybe they'll start on the Shuowen next and then move
>> back to pre-Zhou stuff. :-)

> If they did, would the SIP overflow?

I would guess that few if any characters in the Shuowen are not also
in the Kangxi dictionary and thus not already covered by Unicode 3.
(The exception might be some of Shuowen's 504 bushou (classifiers)
which have been reduced to Kangxi's famous 214 bushou.) Anyway, it
wouldn't take many (in hanzi terms) code points to bring the Shuowen
entirely into the Unicode fold, I think.

But covering the jiaguwen [J. koukotsumoji] (oracle bone script) is
another story. First of all, it's a moving target. And except for
those that have been identified as ancestors of documented graphs
.. and I can't recall what approximate portion that is, perhaps 1/3 of
the available jiaguwen repertoire... the meaning, and certainly the
exact pronunciation as has been noted, is not yet known.